This invention relates to a data processor which is adaptable to an electronic typewriter and a word processor.
A word processor executes simultaneously a text editing process and a printing process. In the former process, key code data input from a keyboard is stored in an input memory in order to edit a text. In the latter process, the data stored in the memory is output to a printer. These two processes are alternately dispatched by a time slice method under the control of a CPU.
However, in this case, key, code data processing in the input memory must wait while processing is simultaneously executed for printing, so the key, code data are temporarily stored in a key buffer. As a result, the key code data entry lags behind quick keying so that a time lag occurs between the keying of data and displaying the data on the screen. If the capacity of the key buffer is too small, key code data entered after the buffer becomes full are lost. It is costly to provide a buffer having a large capacity to prevent this.